Adding to a growing list of amicus briefs filed in favor of Apple's pro-encryption stance in a high-profile legal battle with the FBI, United Nations free speech watchdog David Kaye reportedly plans to lodge a similar document supporting the company's arguments.

The friend of the court brief, a copy of which was obtained by BuzzFeed News on Wednesday, argues "secure communications are fundamental to the exercise of freedom of opinion and expression in the digital age, permitting the maintenance of opinions without interference and securing the right to seek, receive, and impart information and ideas."

As UN special rapporteur, Kaye monitors a wide variety of rights issues —individual rights, media protections, rights for vulnerable communities, activists, political dissenters and more —on a global scale and is in a unique position to offer color on the worldwide implications of the Apple-FBI encryption battle.

Apple in February was ordered by a federal magistrate judge to comply with FBI requests to assist in the unlocking of an iPhone 5c used by Syed Rizwan Farook, one of two shooters responsible for December's San Bernardino terror attack. Cooperation requires Apple create and sign a purposely flawed operating system to suppresses the iPhone's passcode counter and time-sensitive entry limiter to allow a brute-force attack.

In resisting the court order, Apple sparked a nationwide debate over balancing personal liberties with national security.

Citing the International Covenant on Civil and Political Rights (ICCPR), which the U.S. ratified in 1992, Kaye makes the case that the DOJ case rests on shaky ground. In particular, it is unclear that the government's motion to compel is "necessary...for the protection of national security or of public order," a requirement stipulated under Article 19 of the ICCPR.

The government in its case to compel Apple is leveraging the All Writs Act of 1789, a statute granting federal courts sweeping authority to issue orders if no other judicial instruments are available. If the Justice Department is successful, it could set precedent for future cases involving digital evidence.

Article 19 allows for certain restrictions that are deemed necessary and proportionate, but Kaye is concerned an FBI win on the basis of AWA could have implications on the security, and thereby right to free expression, of an untold number of users.

"This is fundamentally a problem with technology, where compromising security for one and only one time and purpose seems exceedingly difficult if not impossible," Kaye writes.